Contact assemblies, methods for making contact assemblies, and plating machines with contact assemblies for plating microelectronic workpieces

ABSTRACT

Contact assemblies, electroplating machines with contact assemblies, and methods for making contact assemblies that are used in the fabrication of microelectronic workpieces. The contact assemblies can be wet-contact assemblies or dry-contact assemblies. A contact assembly for use in an electroplating system can comprise a support member and a contact system coupled to the support member. The support member, for example, can be a ring or another structure that has an inner wall defining an opening configured to allow the workpiece to move through the support member along an access path. In one embodiment, the support member is a conductive ring having a plurality of posts depending from the ring that are spaced apart from one another by gaps. The contact system can be coupled to the posts of the support member. The contact system can have a plurality of contact members projecting inwardly into the opening relative to the support member and transversely with respect to the access path. The contact members can comprise electrically conductive biasing elements, such as fingers, that have a contact site and a dielectric coating covering at least a portion of the biasing elements. The contact members can also have a raised feature configured to engage the seed-layer on the workpiece for conducting the current to the seed-layer.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/354,649 filed Jan. 28, 2003 which is a divisional of U.S. patentapplication Ser. No. 09/717,927 filed Nov. 20, 2000, now. U.S. Pat. No.6,527,925 which is a continuation-in-part PCT Application No.PCT/US99/15847, filed Jul. 12, 1999, which is a continuation of andclaims prionty from U.S. patent application Ser. No. 09/113,723 filedJul. 10, 1998, issued as U.S. Pat. No. 6,080,291, and (b) also claimsthe benefit of U.S. Provisional Application No. 60/111,232 filed Dec. 7,1998 and 60/119,668, filed Feb. 11, 1999.

BACKGROUND

Processors, memory devices, field-emission-displays, read/write headsand other microelectronic devices generally have integrated circuitswith microelectronic components. A large number of individualmicroelectronic devices are generally formed on a semiconductor wafer, aglass substrate, or another type microelectronic workpiece. In a typicalfabrication process, one or more layers of metal are formed on theworkpieces at various stages of fabricating the microelectronic devicesto provide material for constructing interconnects between variouscomponents.

The metal layers can be applied to the workpieces using severaltechniques, such as chemical vapor deposition (CVD), physical vapordeposition (PVD), plasma-enhanced deposition processes, electroplating,and electroless plating. The particular technique for applying a metalto a workpiece is a function of the particular type of metal, thestructure that is being formed on the workpiece, and several otherprocessing parameters. For example, CVD and PVD techniques are oftenused to deposit aluminum, nickel, tungsten, solder, platinum and othermetals. Electroplating and electroless plating techniques can be useddeposit copper, solder, permalloy, gold, silver, platinum and othermetals. Electroplating and electroless plating can be used to formblanket layers and patterned layers. In recent years, processes forplating copper have become increasingly important in fabricatingmicroelectronic devices because copper interconnects provide severaladvantages compared to aluminum and tungsten for high-performancemicroelectronic devices.

Electroplating is typically performed by forming a thin seed-layer ofmetal on a front surface of a microelectronic workpiece, and then usingthe seed-layer as a cathode to plate a metal layer onto the workpiece.The seed-layer can be formed using PVD or CVD processes. The seed-layeris generally formed on a topographical surface having vias, trenches,and/or other features, and the seed-layer is generally approximately1000 angstroms thick. The metal layer is then plated onto the seed-layerusing an electroplating technique to a thickness of approximately 6,000to 15,000 angstroms. As the size of interconnects and othermicroelectronic components decrease, it is becoming increasinglyimportant that a plated metal layer (a) has a uniform thickness acrossthe workpiece, (b) completely fills the vias/trenches, and (c) has anadequate grain size.

Electroplating machines for use in manufacturing microelectronic devicesoften have a number of single-wafer electroplating chambers. A typicalchamber includes a container for holding an electroplating solution, ananode in the container to contact the electroplating solution, and asupport mechanism having a contact assembly with electrical contactsthat engage the seed-layer. The electrical contacts are coupled to apower supply to apply a voltage to the seed-layer. In operation, thefront surface of the workpiece is immersed in the electroplatingsolution so that the anode and the seed-layer establish an electricalfield that causes metal in a diffusion layer at the front surface of theworkpiece to plate onto the seed-layer.

The structure of the contact assembly can significantly influence theuniformity of the plated metal layer because the plating rate across thesurface of the microelectronic workpiece is influenced by thedistribution of the current (the “current density”) across theseed-layer. One factor that affects the current density is thedistribution of the electrical contacts around the perimeter of theworkpiece. In general, a large number of discrete electrical contactsshould contact the seed-layer proximate to the perimeter of theworkpiece to provide a uniform distribution of current around theperimeter of the workpiece. Another factor that affects the currentdensity is the formation of oxides on the seed-layer. Oxides aregenerally resistive, and thus oxides reduce the efficacy of theelectrical connection between the contacts and the seed-layer. Stillother factors that can influence the current density are (a) galvanicetching between the contacts and the seed-layer, (b) plating on thecontacts during a plating cycle, (c) gas bubbles on the seed-layer, and(d) other aspects of electroplating that affect the quality of theconnection between the contacts and the seed-layer or the fluid dynamicsat the surface of the workpiece. The design of the contact assemblyshould address these factors to consistently provide a uniform currentdensity across the workpiece.

One type of contact assembly is a “dry-contact” assembly having aplurality of electrical contacts that are sealed from the electroplatingsolution. For example, U.S. Pat. No. 5,227,041 issued to Brogden et al.discloses a dry contact electroplating structure having a base memberfor immersion into an electroplating solution, a seal ring positionedadjacent to an aperture in the base member, a plurality of contactsarranged in a circle around the seal ring, and a lid that attaches tothe base member. In operation, a workpiece is placed in the base memberso that the front face of the workpiece engages the contacts and theseal ring. When the front face of the workpiece is immersed in theelectroplating solution, the seal ring prevents the electroplatingsolution from contacting the contacts inside the base member. Onemanufacturing concern of dry-contact assemblies is that galvanic etchingoccurs between the contacts and the seed-layer when an electrolytesolution gets into the dry contact area. Galvanic etching removes theseed-layer at the interface of the contacts, which can cause anon-uniform current distribution around the perimeter of the workpiece.Therefore, even though dry-contact assemblies keep the contacts clean,they may produce non-uniform metal layers on the workpieces.

Another type of contact assembly is a “wet-contact” assembly having aplurality of electrical contacts that are exposed to the electroplatingsolution during a plating cycle. Because the contacts are exposed to theelectroplating solution during a plating cycle, the metal in theelectroplating solution also plates onto the contacts. The contacts,however, may plate at different rates such that some contacts can have agreater surface area of conductive material contacting the seed-layer.The in-situ plating of contacts can accordingly reduce the uniformity ofthe metal layer on the workpiece. Additionally, wet-contact assembliesmust be periodically “de-plated” to remove the metal that plates ontothe contacts during a plating cycle. Therefore, it would be desirable todevelop a wet-contact assembly that eliminates or reduces the processingconcerns associated with exposing the contacts to the electroplatingsolution.

SUMMARY

The present invention is generally directed toward contact assemblies,electroplating machines with contact assemblies, and methods for makingcontact assemblies that are used in the fabrication of microelectronicworkpieces. The contact assemblies can be wet-contact assemblies ordry-contact assemblies. In one aspect of the invention, a contactassembly for use in an electroplating system comprises a support memberand a contact system coupled to the support member. The support member,for example, can be a ring or another structure that has an inner walldefining an opening configured to allow the workpiece to move throughthe support member along an access path. In one embodiment, the supportmember is a conductive ring having a plurality of posts that depend fromthe ring and are spaced apart from one another by gaps.

The contact system can be coupled to the posts of the support member.The contact system can have a plurality of contact members projectinginwardly into the opening relative to the support member andtransversely with respect to the access path. The contact members cancomprise electrically conductive biasing elements, such as fingers, thathave a contact site and a dielectric coating configured to expose thecontact sites. In one embodiment, the contact system further comprises aconductive mounting section attached directly to the posts to defineflow paths through the gaps. The contact members can project inwardlyfrom the mounting section along a radius of the opening or at an angleto a radius of the opening to define cantilevered spring elements thatcan support the workpiece. The contact members can also have a raisedfeature configured to engage the seed-layer on the workpiece.

In operation, a workpiece is loaded into the contact assembly byinserting the workpiece through the opening of the support member untilthe front face of the workpiece engages the contact sites on the contactmembers. Because the contact members can be biasing elements that flex,the contact members flex downwardly and transversely relative to theaccess path so that the contact sites adequately engage the seed-layeron the workpiece even though the face of the workpiece may have vias,trenches and other topographical features. The face of the workpiece andthe contact members can then be immersed in an electroplating solutionwhile the contact assembly rotates. Because the contact members areexposed to the electroplating solution, the metal in the solutioncontinuously plates the interface between the contact sites and theseed-layer. The plating of the contact/seed-layer interface mitigatesthe galvanic etching of seed-layer. Additionally, several embodiments ofcontact members have a dielectric coating with stepped edges adjacent tothe contact site that inhibit the metal from plating over the dielectriclayer. The stepped edges accordingly reduce the problems associated withde-plating the contacts. Also, in embodiments that have a raised featureon the contact members, the electroplating solution can flow morereadily between the contact members and the workpiece to reduce platingon the contact members. Therefore, several embodiments of contactassemblies are expected to enhance the quality and throughput ofelectroplating microelectronic workpieces.

BRIEF DESCRIPTION THE DRAWINGS

FIG. 1 is an isometric view with a cut-away portion of an electroplatingmachine having a contact assembly in accordance with one embodiment ofthe invention.

FIG. 2 is a cross-sectional view of an electroplating chamber having acontact assembly for use in an electroplating machine in accordance withan embodiment of the invention.

FIG. 3 is an isometric view illustrating a portion of a contact assemblyfor use in an electroplating machine in accordance with an embodiment ofthe invention.

FIG. 4 is an isometric view illustrating a cross-section of a contactassembly for use in an electroplating machine in accordance with anembodiment of the invention.

FIG. 5 is a cross-sectional view of a portion of the contact assembly ofFIG. 4 illustrating a contact member in accordance with an embodiment ofthe invention in greater detail.

FIG. 6 is an isometric view illustrating a portion of a contact assemblyfor use in an electroplating machine in accordance with anotherembodiment of the invention.

FIG. 7 is top plan view of a contact assembly for use in anelectroplating machine in accordance with another embodiment of theinvention.

FIG. 8 is an isometric view of a contact assembly for use in anelectroplating machine in accordance with another embodiment of theinvention.

FIG. 9 is a top plan view of a contact system for use in a contactassembly in accordance with an embodiment of the invention.

FIGS. 10 and 11 are cross-sectional views of contact members for contactassemblies in accordance with additional embodiments of the invention.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

The following description discloses the details and features of severalembodiments of contact assemblies, methods for making contactassemblies, and electroplating machines with contact assemblies forelectroplating metal layers onto microelectronic workpieces. It will beappreciated that several of the details set forth below are provided todescribe the foregoing embodiments in a manner sufficient to enable aperson skilled in the art to make and use contact assemblies andelectroplating systems in accordance with embodiments of the invention.Several of the details and advantages described below, however, may notbe necessary to practice embodiments of the invention accordance withthe following claims. For example, many of the embodiments describedbelow are directed toward wet-contact assemblies, but these same devicescan also be used in dry-contact assemblies as shown in PCT ApplicationNo. PCT/US99/15847. Additionally, the invention can also includeadditional embodiments that are within the scope of the claims but arenot described in detail with respect to FIGS. 1-11.

The operation and features of the contact assemblies are best understoodin light of the environment and equipment in which they can be used toelectroplate workpieces. As such, several embodiments of electroplatingtools and reaction chambers that can be used with the contact assemblieswill be described with reference to FIGS. 1 and 2. The details andfeatures of several embodiments of contact assemblies will then bedescribed with reference to FIGS. 3-11.

A. Selected Embodiments of Electroplating Machines and Reactor Chambersfor Use With Contact Assemblies to Electroplate Metals ontoMicroelectronic Workpieces

FIG. 1 is a front isometric view of an electroplating machine 100 inwhich contact assemblies in accordance with embodiments of the inventioncan be used. The electroplating machine 100 can include a cabinet 102, aload/unload mechanism 104 at one end of the cabinet 102, and a pluralityof chambers 110 in the cabinet 102. The chambers 110 can includeelectroplating chambers 112, electroless plating chambers 114, and/orrapid thermal annealing chambers 118. The electroplating chambers 112can include a contact assembly (not shown in FIG. 1) to apply anelectrical potential to a seed-layer on the workpiece. Theelectroplating machine 100 can also include a transfer mechanism 120having a rail or track 122 and a plurality of robots 124 that move alongthe track 122. The robots 124 include arms 126 that can carry amicroelectronic workpiece 130 between the chambers 110. In operation,the load/unload mechanism 104 positions a cassette holding a pluralityof workpieces in the cabinet 102, and the transfer mechanism 120 handlesthe individual workpieces 130 inside the cabinet 102. The transfermechanism 120, for example, can initially place the workpiece 130 in anelectroless plating chamber 114 to repair or enhance the seed-layer onthe workpiece. The transfer mechanism 120 can then remove the workpiece130 from the electroless plating chamber 114 and place it in theelectroplating chamber 112 for forming a blanket layer or a patternedlayer on the front face of the workpiece 130. In an alternativeembodiment, the transfer mechanism can be a radial system such as in theEQUINOX® machines manufactured by Semitool, Inc. of Kalispell, Mont.After the electroplating cycle, the transfer mechanism 120 can removethe workpiece 130 from the electroplating chamber 112 and transfer it toanother processing station in the machine 100 (e.g., a standardrinser-dryer, a rinse/etch capsule, an annealing chamber, etc.) or placeit in the cassette.

FIG. 2 is a partial cross-sectional view of an electroplating chamber112 having a contact assembly 200 in accordance with one embodiment ofthe invention for supporting and providing an electrical connection to afront face of the workpiece 130. For the purposes of brevity, severalcomponents of the electroplating chamber 112 are shown schematically orby line drawings. Many of the particular features of the componentsshown schematically are described more detail in the patent applicationsincorporated by reference. The electroplating chamber 112 can include abowl 140 configured to contain an electroplating solution, an anode 150in the bowl 140, and a head assembly 170 that carries the contactassembly 200. The head assembly 170 is movable with respect to the bowl140 to position the workpiece 130 in the plating solution (not shown).In the embodiment shown in FIG. 2, the head assembly 170 is shown in apartially inserted position in which the contact assembly 200 and theworkpiece 130 are at a slight angle. When the head assembly 170 is fullyinserted into the bowl 140, a beveled surface 172 of the head assembly170 is superimposed over a corresponding beveled surface 142 of the bowl140, and the contact assembly 200 holds the workpiece 130 in a desiredposition relative to the plating solution.

The bowl 140 can include a cup 144 having an overflow wier 146. Theanode 150 is positioned in the cup 144, and the anode 150 can beattached to an anode support assembly 152. In one embodiment, the anodesupport assembly 152 has a channel 154 through which the electroplatingsolution flows and is discharged into the cup 144. The anode supportassembly 152 can be electrically conductive, or it can include aconductor to electrically couple the anode 150 to a power supply. Inoperation, a flow of plating solution (identified schematically byarrows “S”) passes through the anode support assembly 152 and isdischarged into the cup 144 underneath the anode 150. The platingsolution flow S continues around the anode 150, over the wier 146, andinto a lower portion of the bowl 140. As the plating solution flow Spasses over the wier 146, it forms a meniscus at the top of the cup 144.The plating solution flow S can then pass out of the bowl 140 where itis filtered and reconditioned so that the plating solution can bere-circulated through the cup 144. Suitable embodiments of bowls 140,cups 144, anodes 150 and anode support assemblies 152 are described inPCT Application Nos. PCT/US99/15430 and PCT/US00/10210, which are hereinincorporated by reference.

The head assembly 170 can further include a motor 174 and a rotor 180that carries the contact assembly 200. The motor 174 is coupled to therotor 180 to rotate the contact assembly 200 and the workpiece 130during a plating cycle (Arrow R). The rotor 180 can include a movablebacking plate 182 and a seal 184. The backing plate 182 can movetransverse to the workpiece 130 (Arrow T) between a first position inwhich the backing plate 182 engages the back side of the workpiece 130(shown in solid lines in FIG. 2) and a second position in which it isspaced apart from the back side of the workpiece 130 (shown in brokenlines in FIG. 2). In this embodiment, the contact assembly 200 iscoupled to the rotor 180 by a plurality of shafts 202 that are receivedin quick-release mechanisms 204. The shafts 202 can be rigid, conductivemembers that electrically couple the contact assembly 200 to anelectrical potential so that the seed-layer on the workpiece 130 is acathode.

In operation, the head assembly 170 can be initially raised above thebowl 140 and rotated about a relatively horizontal axis to position thecontact assembly 200 to face upward away from the bowl 140. The backingplate 182 is moved to the second position in which it is spaced apartfrom the contact assembly 200 to load the workpiece 130 into the headassembly 170. The robot 124 (FIG. 1) inserts the workpiece 130 face-upinto the contact assembly 200, and then the backing plate 182 moves tothe first position in which it presses the workpiece 130 against thecontact assembly 200. The head assembly 170 then rotates about thehorizontal axis to position the contact assembly 200 face downward andlowers the loaded workpiece 130 and a portion of the contact assembly200 into the plating solution proximate to the overflow wier 146. Themotor 174 rotates the rotor 180 about a relatively vertical axis to movethe workpiece 130 in the plating solution during the plating cycle.After the plating cycle is complete, the head assembly 170 removes theworkpiece 130 from the plating solution so that it can be rinsed and/ortransferred to another processing chamber or machine. In an alternativeembodiment, the head assembly does not rotate about the horizontal axisto position the contact assembly 200 face-up during a load/unloadsequence such that the workpiece is loaded into the contact assemblyface-down toward the bowl 140.

The foregoing description of the electroplating machine 100 and theelectroplating chamber 112 provides examples of the types of devices inwhich contact assemblies in accordance with embodiments of the inventioncan be used to plate metal layers onto microelectronic workpieces. Itwill be appreciated that the contact assembly 200, and other embodimentsof contact assemblies described in more detail below, can be used withother electroplating machines and reaction chambers.

B. Selected Embodiments of Contact Assemblies for ElectroplatingMicroelectronic Workpieces

FIGS. 3-11 illustrate several embodiment contact assemblies that can beused in the electroplating chamber 112 of the electroplating machine100. The structures and operation of the contact assemblies shown inFIGS. 3-11 are generally described with reference to wet-contactassemblies. It will be appreciated, however, that they can also beconfigured to be dry-contact assemblies. Therefore, the basic structureis applicable to both wet-contact and dry-contact electroplatingapplications.

FIG. 3 is an isometric view showing the features of an embodiment of thecontact assembly 200 in greater detail. In this embodiment, the contactassembly 200 has a support member 210 and a contact system 250 attachedto the support member 210. The shafts 202 can be connected to thesupport member 210 to attach the contact assembly 200 to the headassembly 170 (FIG. 2). The support member 210 can have a circular shape,a shape with one or more straight-edge sections, or any other suitableshape corresponding to the shape of the workpiece. The embodiment of thesupport member 210 shown in FIG. 2 is a ring having an inner wall 212defining an opening that is configured to allow the workpiece 130 (FIG.2) to move through the support member 210 along an access path “P.” Thesupport member 210 can be formed from a conductive material, such astitanium, stainless-steel, or another suitable metal. In an alternativeembodiment, the support member 210 can be formed from a dielectricmaterial and further include conductive lines extending through thedielectric material. In this embodiment, the support member 210 includesa plurality of posts 214 and workpiece guides 216. The posts 214 projectdownwardly from the main portion of the conductive ring, and the posts214 can have squared corners or rounded corners. The posts 214 can alsohave rectilinear or circular cross-sections, and in one embodiment theposts are approximately 0.10-0.40 inch wide. The posts 214 are spacedapart from one another by gaps 218 that provide passageways for gasbubbles and electroplating solution to pass through the support member210 during a plating cycle. In one particular embodiment, the gaps areapproximately 0.10-0.30 inch high and 0.10-0.25 inch wide. The workpieceguides 216 can be positioned around the interior of the support member210 at selected radial increments, such as 15°, 30°, 60°, etc. Theworkpiece guides 216 can have a tapered surface 219 that slopes into theopening for guiding the workpiece 130 onto the contact system 250. Theworkpiece guides 216 can include other embodiments or be arranged aroundthe interior of the support member 210 in different patterns, and theposts 214 and the gaps 218 can have different sizes and shapes thanthose set forth above.

The contact system 250 can comprise a conductive mounting section 252and a plurality of contact members 254 projecting from the mountingsection 252 into the opening defined by the support member 210. Themounting section 252, for example, can be a ring that is connected tothe posts 214 of the support member 210 by spot welds, screws, or othersuitable techniques. The mounting section 252 can alternatively be asegment, such as an arcuate segment of a ring, and a plurality ofseparate segments can be attached to the posts 214 of the support member210. The mounting section 252 and the contact members 254 can be formedfrom an electrically conductive material and/or have a suitableelectrically conductive coating. In one embodiment, the mounting section252 and a contact members 254 are made from a sheet of metal, such astitanium, stainless-steel, or another suitably conductive material thatcan flex under the loads generated by the backing plate 182 as itpresses the workpiece 130 against the contact members 254.

The contact members 254 can be conductive biasing elements that projectinwardly into the opening defined by the inner wall 212 of the supportmember 210 and transversely with respect to the access path P. In oneembodiment, the contact members 254 are cantilevered spring elements.The contact members 254 can be integral with the mounting section 252,or they can be individual fingers that are attached to the mountingsection 252 by spot welds or other suitable fasteners. In thisembodiment, the contact members 254 are cantilevered spring elements orfingers that project inwardly along a radius of the support member 210.

FIG. 4 is a partial isometric view that illustrates an embodiment of thesupport member 210, the mounting section 252, and the contact members254 in greater detail. The posts 214 of the support member 210 can havean angled lower surface that projects upwardly with respect to theaccess path P. Additionally, the mounting section 252 and the contactmembers 254 can be formed to have a conical shape that angles upwardlysuch that the contact members 254 also project upwardly with respect tothe access path P. The upward angle is approximately 5°-15°, and morespecifically can be approximately 8°. In an alternative embodiment, thesupport members 254 can extend approximately normal to the access pathP. In operation, the backing member 182 (FIG. 2) drives the workpiece130 downward along the access path P causing the contact members 254 toflex downwardly and slide transversely across the surface of theworkpiece 130. The downward flexing of the contact members 254 allowsthe contact members 254 to conform to a topographical surface of theworkpiece 130, and the sliding of the contact members 254 removes oxidesthat may have grown on the seed-layer.

FIG. 5 is a cross-sectional view illustrating a portion of an embodimentof the contact assembly 200 that is particularly well-suited for use asa wet-contact assembly in which the contact system 250 and a portion ofthe support member 210 are submerged in a plating solution. In thisembodiment, the mounting section 252 and the contact members 254 arestamped or otherwise formed from a sheet of titanium or another suitableconductive material so that the mounting section 252 and the contactmembers 254 are integral with one another. The mounting section 252 andthe contact members 254 can be coated with a layer of a conductivecontact material 256. One suitable metal for the contact layer 256 isplatinum, but other metals that interact with the plating solution andthe seed-layer in a desired manner can be used. The support member 210and the contact system 250 can then be coated with a dielectric coating257. The dielectric coating 257 is generally selected according to (a)the compatibility with the plating solution, (b) adhesion to the metalof the contact system 250, and (c) ability to effectively coat thecontact system 250. Suitable materials that can be used for thedielectric coating 257 include (a) an 8840 primer and a Teflondielectric exterior coating manufactured by DuPont® (“DuPont”); (b) an8840 green coating manufactured by DuPont; (c) a 954-100 epoxy basedcoating manufactured by DuPont; (d) a 954-101 epoxy based coatingmanufactured by DuPont; (e) HALAR® coatings under the name Dycore® 404;(f) KYNAR® coatings under the identification Dycore® 202 either with orwithout a primer of Dycore 204; (g) HALAR® heavy coatings; (h)FLUOROLON® 109 distributed by Southwest Impreglon® Sales, Inc. of Texas;(i) Impreglon 216® or Impreglon 872® distributed by Southwest Impreglon®Sales, Inc.; and (j) other epoxy based coatings, thermoplasticcopolymers, or fluorocarbon resins. It will be appreciated that othermaterials can be used for the dielectric coating 257, and thus theforegoing materials provide examples that are not intended to limit theclaims.

The contact members 254 can also have an aperture 258 formed in thedielectric coating 257 at a contact site 259 to expose a portion of thecontact layer 256. The aperture 258 can be formed by laser ablatingtechniques that consume the dielectric coating 257 to form stepped edgesat the aperture 258. Laser ablating techniques can be closely controlledso that the dielectric coating 257 can be removed from the contact layer256 without damaging or impairing the performance of the contact layer256. For example, the energy and/or wavelength of the laser can beselected so that it consumes the dielectric coating 257 withoutaffecting the contact layer 256. Additionally, the residence time thatthe laser impinges the dielectric coating 257 can be controlled so thatthe laser is moved before it consumes the contact layer 256. Theaperture 258 can alternatively be formed using machining techniques. Ineither case, the dielectric coating 257 does not cover the contact site259 so that the contact member 254 can provide an electrical potentialto the seed-layer on the workpiece 130.

FIGS. 2 and 3 illustrate the operation and advantages of severalembodiments of the contact assembly 200. Referring to FIG. 2, when thehead assembly 170 rotates the workpiece 130, the plating solution at thefront face of the workpiece 130 is driven radially outwardly toward thesupport member 210. Referring to FIG. 3, the plating solution and anygas bubbles at the surface of the workpiece 130 pass through the gaps218 of the support member 210. An electrical potential is also appliedto seed-layer on the workpiece via the contact system 250 to establish acurrent field between the anode 150 and the seed-layer. The currentbetween the anode 150 and the seed-layer causes the metal in the platingsolution to plate onto the seed-layer and portions of the contactmembers 254 because the contact members 254 are also exposed to theplating solution. After an adequate layer of metal has been plated ontothe workpiece 130, the head assembly 170 raises the contact assembly 200to an intermediate elevation at which a rinsing solution is applied tothe workpiece 130 as it continues to rotate. The head assembly 170 isthen raised to clear the upper lip of the bowl 140, and the workpiece130 is removed from the contact assembly 200. The head assembly 170 canthen be re-lowered to submerge the contact assembly 200 in the platingsolution for de-plating the contact members 254 by switching thepotential applied to the contact members 254 so that the contact members254 are the anode and applying an opposite potential to a ring cathode270 in the bowl 140.

When the contact assembly 200 is used in a wet-contact environment,several embodiments of the contact assembly 200 reduce galvanic etchingof the seed-layer at the interface between the contact members and theseed-layer compared to dry-contact assemblies. Because the contactassembly 200 has contact members 254 coated with a dielectric material,it can be a “wet-contact” assembly in which the contact members 254 areexposed to the plating solution. The etching caused by the galvaniceffect between the seed-layer and the contact members 254 before beingimmersed in the plating solution does not occur after the contactassembly 200 is placed in the plating solution. Therefore, severalembodiments of the contact assembly 200 are expected to provide auniform current distribution around the perimeter of the workpiecethroughout a plating cycle to enhance the uniformity of the platedlayer.

Several embodiments of the contact assembly 200 also provide a largenumber of contacts that uniformly engage the perimeter of the workpiece.Because the contact members 254 flex downwardly as the workpiece isloaded into the contact assembly 200, the contact members 254 cancompensate for topographical variances across the surface of theworkpiece to provide a uniform pressure against the various contactpoints on seed-layer. Additionally, the large number of individualcontact members 254 enhance the uniformity of the electrical potentialaround the perimeter of the workpiece. Therefore, several embodiments ofthe contact assembly 200 are expected to further enhance the uniformityof the plated layer by providing a large number of contact members 254that can adapt to different topographical features on the workpiece.

Several embodiments of the contact assembly 200 used for wet-contactapplications reduce non-uniformities caused by bubbles in the platingsolution. One problem of electroplating is that bubbles can form on theanode 150 (FIG. 2) and rise through the plating solution to the face ofthe workpiece 130. Air can also be trapped on the face of the workpiece130 as it is lowered into the plating solution. As the workpiece 130rotates through the plating solution, the bubbles are driven radiallyoutward toward the perimeter of the workpiece. If the bubbles aretrapped at the perimeter of the workpiece, they can prevent the platingsolution from contacting the workpiece in a manner that causesnon-uniform plating. The contact assembly 200 mitigates this problembecause any such bubbles can flow through the gaps 218 between the posts214 of the support member 210. Therefore, several embodiments of thecontact assembly 200 are expected to reduce non-uniformities caused bybubbles in the plating solution.

Selected embodiments of the contact assembly 200 also enhance theuniformity of the electrical interface between the contact members 254and the seed-layer by mechanically impairing the metal from plating overthe dielectric coating 257 adjacent to the contact sites 259. Anotherproblem of using a conventional wet-contact assembly is that the metalcan plate over the dielectric coating during the plating cycle. Themetal that plates over the dielectric coating may not be completelyremoved during a de-plating cycle, or it can increase the duration ofthe de-plating cycle causing a reduction in throughput of theelectroplating machine. In embodiments of the contact assembly 200 inwhich the dielectric coating 257 is removed from the contact sites 259using laser ablating techniques, the stepped edge of the aperture 258creates a step-height that inhibits the metal from plating onto thedielectric coating 257 adjacent to the aperture 258. Laser ablatedapertures 258 accordingly eliminate or at least reduce the amount ofmetal that must be removed by the deplating process. Therefore, certainembodiments of the contact assembly 200 are expected to enhance theefficacy of de-plating processes to provide a more consistent electricalinterface between the contact members 254 and the seed-layer.

FIG. 6 is a partial isometric view of a contact assembly 300 inaccordance with another embodiment of the invention. The contactassembly 300 can include a support member 310 and a contact system 350comprising a plurality of individual, separate contact members 354. Thesupport member 310 can be substantially similar to the support member210 described above. The support member 310 can accordingly have aninner wall 312 defining an opening configured to receive the workpiece130 and a plurality of posts 314 that are spaced apart from one anotherby gaps 318. The individual contact members 354 can be similar to thecontact members 254 described above with reference to FIGS. 4 and 5,except that the individual contact members 354 have individual mountingsections 356 attached to the posts 314 by spot welds or other suitablefasteners. The contact system 350 accordingly does not include amounting section spanning between the posts 314. The support member 310and the contact members 354 can be coated with the same coatingsdescribed above with reference to FIGS. 4 and 5. The contact assembly300 operates in a manner that is similar to the contact assembly 200described above, and several embodiments of the contact assembly 300 mayalso provide similar advantages as the contact assembly 200.

FIG. 7 is a top plan view of a contact assembly 400 in accordance withanother embodiment of the invention. The contact assembly 400 caninclude a support member 410 and a contact system 450 attached to thesupport member 410. The support member 410 can be a conductive ringhaving a plurality of downwardly depending posts (not shown in FIG. 7)that are separated from one another by gaps similar to the posts 214shown in FIG. 3.

The support member 410 also has a plurality of guides 416 that arearranged in a first guide pair 420, a second guide pair 422, and a thirdguide pair 424. In this embodiment, the guide pairs 420, 422, and 424are spaced apart from one another by approximately 120° around theinterior of the support member 410. The first guide pair 420 can bespaced 60° apart from one of the contact shafts 202, and the secondguide pair 422 can be spaced 60° apart from the other contact shaft 202on the same side of the support member 410. The third guide pair 424 canbe spaced equally between the contact shafts 202 on the other side ofthe support member 410. This spacing of the guide pairs inhibits theplating solution from wicking up the guides 416 and onto the back sideof the workpiece as the head assembly 170 (FIG. 2) lowers one side ofthe contact assembly 400 into the plating solution at an angle relativeto the overflow wier 146 (see the contact assembly 200 shown in FIG. 2).For example, if the contact assembly 400 shown in FIG. 7 is attached tothe head assembly 170 shown in FIG. 2 so that a first region 430 of thecontact assembly 400 is lowered into the plating solution and then asecond region 432 is the final portion of the contact assembly 400lowered into the solution, then the guides 416 are spaced apart from thefirst region 430 so that the plating solution does not wick up betweenthe guides 416 and the workpiece. If the guides 416 were located at thefirst region 430, then the plating solution may wick up the guides andonto the backside of the workpiece.

The guides 416 are not limited to the arrangement shown in FIG. 7. Theguides 416, for example, can be arranged individually or in pairs sothat the guides 416 are generally spaced apart from the portion of thecontact assembly that is (a) initially submerged in the plating solutionand/or (b) submerged to the greatest depth in the plating solution.Therefore, the contact assembly 400 may have additional embodiments thatinhibit contamination of the backside of the workpiece caused by wickingof the plating solution.

FIG. 8 is an isometric view of a contact assembly 500 in accordance withanother embodiment of the invention for use in a reactor chamber of aplating machine. The contact assembly 500 can have a support member 510and a contact system 550 comprising a plurality of swept or angledcontact members 554. The support member 510 can have an inner wall 512defining an opening for receiving the workpiece, a plurality of posts514 spaced apart from one another by gaps 518, and a plurality of guides516 arranged around the inner wall 512. The posts 514 can besubstantially the same as the posts 214, and the guides 516 can bearranged as set forth above in FIG. 3 or 7. In FIG. 8, morespecifically, the guides 516 are arranged in guide pairs to inhibitwicking of the plating solution. The contact system 550 is attached tothe posts 514 of the support member 510 so that bubbles can flow throughthe gaps 518 in the support member 510.

FIG. 9 is a top plan view illustrating a portion of an embodiment of thecontact system 550 in greater detail. Referring to FIGS. 8 and 9together, the contact system 550 can further comprise a mounting section552, such as an arcuate ring, a segment of an arcuate ring, or anotherstructure for mounting the contact members 554 to the support structure510. The contact members 554 can project from the mounting section 552inwardly into the opening of the support member 510 at an angle relativeto a radius of the support member 510. Additionally, the contact members554 can project upwardly in a manner similar to the contact member 254shown in FIG. 4. The support member 510 and the contact system 550 canbe made from and coated with the materials set forth above with respectto the contact assembly 200. As such, the contact members 554 can have acontact site 559 for contacting the seed-layer on the workpiece.

The contact assembly 500 is expected to provide a good electricalconnection between the contact members 554 and the seed-layer on theworkpiece. One aspect of plating microelectronic workpieces is that thereal estate on the front face of the workpiece should be used to formfeatures, and thus the contact members 554 should not extend too farinward from the perimeter of the workpiece. It is also generallydesirable that the contact members have a relatively long lever arm sothat they flex easily as the workpiece presses against them. The contactsystem 550 provides a solution to increase the length of the lever armof the contact member 554 without extending further inwardly beyond theperimeter of the workpiece by angling the contact member 554 relative todiametric lines of the support member 510. Therefore, the contactmembers 554 have desirable flexural qualities without affecting theavailable real estate on the workpiece for fabricating devices.

The contact assembly 500 is also expected to provide a desirable flow ofthe plating solution at the perimeter of the workpiece. In operation,the workpiece is rotated in a direction R so that the inward edges 560of the contact members 554 drive the plating solution toward theinterior of the workpiece. The swept contact members 554 accordinglydrive the plating solution away from the perimeter, and the sweptcontact members 554 are expected to produce less turbulence at theperimeter than radially projecting contact members. As a result, theswept contact members 554 are expected to provide a desirable flow ofthe plating solution at the perimeter of the workpiece.

FIG. 10 is a cross-sectional view of a contact member 754 comprising abiasing element 755 having a raised feature 780 at a contact site 760for contacting the seed-layer of the workpiece. The biasing element 755can be a finger made from titanium or another suitable conductivematerial with desirable structural qualities. A conductive contact layer756 can coat the biasing element 755, and a dielectric coating 758 cancover the contact layer 756. The contact layer 756 can be platinum oranother suitable metal, and the dielectric coating 758 can be one of thecoatings described above. The dielectric coating 758 can be removed fromthe contact site 760 to expose the contact layer 756 on the raisedfeature 780 using a laser ablation technique. As a result, thedielectric coating 758 can have an aperture 759 with a stepped edge toinhibit the metal in the plating solution from plating over thedielectric coating 758 adjacent to the aperture 759. In this embodiment,the raised feature 780 is a deformed portion of the biasing element 755,and the contact layer is a conformal layer that is plated onto thebiasing element 755.

FIG. 11 is a cross-sectional view of a contact member 854 having abiasing element 855 with a raised feature 880 at a contact site 860. Thebiasing element 855 can be a finger that is coated with a dielectriclayer 858. In this embodiment, the dielectric layer 858 has an aperture859 at the contact site 860, and the raised feature 880 is a bump ofcontact material deposited at the contact site 860. The raised feature880, for example, can be a platinum bump. The contact members 254, 354and 554 described above can have the structure of the contact members754 or 854 shown in FIGS. 10 and 11.

Several embodiments of the contact member 754 an 854 are expected toprovide a more consistent, uniform electrical connection between thecontact assembly and the seed-layer in wet-contact plating processes.The raised features on the contact members space the workpiece apartfrom the contact members so that the plating solution can flow moreeasily adjacent to the contact points. The increased flow of the platingsolution reduces the size of the diffusion layer at the contact pointsin a manner that reduces plating onto the contact sites and over thedielectric coating adjacent to the contact sites. Such a reduction inplating at the contact sites should provide a consistent electricalconnection throughout a plating cycle to provide a more uniform currentdistribution around the perimeter of the workpiece. Also, a reduction inplating on the contact members is expected to reduce the time expendedfor de-plating the contact assembly. Thus, contact members with raisedfeatures should increase both the uniformity of the current distributionand the throughput of electroplating processes.

From the foregoing it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. Accordingly, the invention is notlimited except by the appended claims.

1. A reactor for electrochemical deposition processing ofmicroelectronic workpieces, comprising: a bowl configured to hold aplating solution; an anode assembly in the reactor at a location to bein fluid communication with the plating solution in the bowl; a headassembly moveable relative to the bowl between a first position toload/unload a workpiece and a second position to place at least aportion of the workpiece in the plating solution; and a contact assemblycomprising a support member and a contact system, wherein the supportmember has an inner wall defining an opening configured to allow theworkpiece to move through the support member along an access path and aplurality of passageways configured to direct gas bubbles and/orelectroplating solution through the contact assembly, and the contactsystem is coupled to the support member, wherein the contact system hasat least one curved conductive mounting section attached to the supportmember and a plurality of contact members integral with the conductivemounting section projecting inwardly into the opening relative to thesupport member and transversely with respect to the access path, andwherein each contact member has a contact site configured toelectrically contact the workpiece inwardly relative to the passageways.2. The reactor of claim 1 wherein the contact members comprisecantilevered spring elements projecting upwardly into the opening. 3.The reactor of claim 1 wherein the contact members comprise cantileveredspring elements projecting upwardly into the opening, and thecantilevered spring elements have a raised feature.
 4. The reactor ofclaim 1 wherein the contact members comprise cantilevered springelements projecting upwardly into the opening, and the cantileveredspring elements have a raised feature comprising a section of the springelements shaped to be the only portion of the spring elements thatcontacts the workpiece.
 5. The reactor of claim 1 wherein the contactmembers comprise cantilevered spring elements projecting upwardly intothe opening, and the cantilevered spring elements have a raised featurecomprising a bump of a separate material on the spring elements.
 6. Thereactor of claim 1 wherein: the support member comprises a ring and aplurality of posts depending from the ring that are separated from oneanother by gaps; and the conductive mounting section comprises at leastone conductive arcuate element attached directly to the posts to defineflow paths through the gaps and the contact members comprise fingersintegral with the arcuate element that project inwardly into the openingalong a radius of the ring.
 7. The reactor of claim 1 wherein: thesupport member comprises a ring and a plurality of posts depending fromthe ring that are separated from one another by gaps; and the conductivemounting section comprises at least one conductive arcuate elementattached directly to the posts to define flow paths through the gaps andthe contact members comprise fingers integral with the arcuate elementthat project inwardly into the opening along a radius of the ring, andwherein the fingers have a raised contact feature.
 8. The reactor ofclaim 1 wherein: the support member comprises a ring and a plurality ofposts depending from the ring that are separated from one another bygaps; and the conductive mounting section comprises at least oneconductive arcuate element attached directly to the posts to define flowpaths through the gaps and the contact members comprise fingers integralwith the arcuate element that project inwardly into the opening at anangle relative to a radius of the ring.
 9. The reactor of claim 1wherein: the support member comprises a ring and a plurality of postsdepending from the ring that are separated from one another by gaps; andthe conductive mounting section comprises at least one conductivearcuate element attached directly to the posts to define flow pathsthrough the gaps and the contact members comprise fingers integral withthe arcuate element that project inwardly into the opening at an anglerelative to a radius of the ring, and wherein the fingers have a raisedfeature.
 10. A reactor for electrochemical deposition processing ofmicroelectronic workpieces, comprising: a bowl configured to hold aplating solution; an anode assembly in the reactor at a location to bein fluid communication with the plating solution in the bowl; a headassembly moveable relative to the bowl between a first position toload/unload a workpiece and a second position to place at least aportion of the workpiece in the plating solution; and a contact assemblycomprising a support member and a contact system, wherein the supportmember has an inner wall defining an opening configured to allow theworkpiece to move through the support member along an access path; andthe contact system is coupled to the support member, wherein the contactsystem comprises at least one conductive mounting section having aconical shape and a plurality of contact members projecting from theconductive mounting section inwardly into the opening relative to thesupport member to contact a peripheral portion of the workpiece, andwherein the contact members are configured to be immersed in a platingsolution during a plating cycle.
 11. The reactor of claim 10 wherein thecontact members comprise cantilevered spring elements projectingupwardly into the opening, a contact site on the spring elements, and adielectric coating on the spring elements that is configured to exposethat contact sites.
 12. The reactor of claim 11 wherein the cantileveredspring elements have a raised feature.
 13. The reactor of claim 11wherein the cantilevered spring elements have a raised featurecomprising a section of the spring elements shaped to be the onlyportion of the spring elements that contacts the workpiece.
 14. Thereactor of claim 11 wherein the cantilevered spring elements have araised feature comprising a bump of a separate material on the springelements.
 15. The reactor of claim 10 wherein: the support membercomprises a conductive support ring having posts projecting from thesupport ring and gaps between the posts; the conductive mounting sectionis attached directly to the posts; and the contact members are fingersintegral with the mounting section, and each finger has a contact siteconfigured to electrically contact the workpiece.
 16. The reactor ofclaim 15 wherein the mounting section comprises at least one arcuateelement and the fingers project inwardly from the arcuate element alonga radius of the support ring, and the fingers have a raised contactfeature at the contact sites.
 17. The reactor of claim 15 wherein themounting section comprises at least one arcuate element and the fingersproject inwardly from the arcuate element at an angle relative to aradius of the support ring, and the fingers have a raised contactfeature at the contact sites.
 18. The reactor of claim 10 wherein: thesupport member comprises a ring and a plurality of posts depending fromthe ring that are separated from one another by gaps; the contactassembly further comprises at least one conductive arcuate elementattached directly to the posts to define flow paths through the gaps andthe contact members comprise fingers integral with the arcuate elementthat project inwardly into the opening; and the support member and thecontact assembly are coated with a dielectric coating that is configuredto expose contact sites on the fingers.
 19. The reactor of claim 18wherein the fingers project inwardly into the opening along a radius ofthe ring and have a raised contact feature.
 20. The reactor of claim 18wherein the fingers project inwardly into the opening at an anglerelative to a radius of the ring.
 21. The reactor of claim 18 whereinthe fingers project inwardly into the opening at an angle relative to aradius of the ring and have a raised feature.
 22. A reactor forelectrochemical deposition processing of microelectronic workpieces,comprising: a bowl configured to hold a plating solution; an anodeassembly in the reactor at a location to be in fluid communication withthe plating solution in the bowl; a head assembly moveable relative tothe bowl between a first position to load/unload a workpiece and asecond position to place at least a portion of the workpiece in theplating solution; and a contact assembly comprising a conductive supportmember and a contact system, wherein the support member having aconductive ring with an inner wall defining an opening configured toallow the workpiece to move through the support member along an accesspath; and the contact system comprises at least one conductive arcuatemounting section coupled to the conductive ring, a plurality ofconductive cantilevered spring elements projecting from the conductivearcuate mounting section inwardly into the opening relative to the ringand transversely with respect to the access path, a dielectric coatingcovering at least a portion of the spring elements, and an electricallyconductive contact site on each spring element exposed through thedielectric coating.
 23. A reactor for electrochemical depositionprocessing of microelectronic workpieces, comprising: a bowl configuredto hold a plating solution; an anode assembly in the reactor at alocation to be in fluid communication with the plating solution in thebowl; a head assembly moveable relative to the bowl between a firstposition to load/unload a workpiece and a second position to place atleast a portion of the workpiece in the plating solution; and a contactassembly comprising a support member and a contact system, wherein thesupport member has an inner wall defining an opening configured to allowthe workpiece to move through the support member along an access pathand a plurality of passageways configured to direct electroplatingsolution through the contact assembly; and the contact system is coupledto the support member, wherein the contact system comprises a pluralityof contact members attached to the support member and positionedinwardly into the opening relative to the support member to contact aperipheral portion of the workpiece, and wherein the contact memberscomprise electrically conductive fingers and raised contact sitesprojecting from the fingers.
 24. The reactor of claim 23 wherein theraised contact sites comprise sections of the fingers configured suchthat the raised contact sites are the only sections of the fingers thatcontact the workpiece.
 25. The reactor of claim 23 wherein the raisedcontact sites comprise a bump of a separate material on the fingers. 26.The reactor of claim 23 wherein: the support member comprises a ring anda plurality of posts depending from the ring that are separated from oneanother by gaps; and the contact assembly further comprises at least oneconductive arcuate element attached directly to the posts to define flowpaths through the gaps and the fingers are integral with the arcuateelement, wherein the contact assembly is coated with a dielectriccoating configured to expose contact sites on the fingers.
 27. Thereactor of claim 23 wherein the fingers project inwardly into theopening along a radius of the ring.
 28. The reactor of claim 23 whereinthe fingers project inwardly into the opening at an angle relative to aradius of the ring.
 29. A reactor for electrochemical depositionprocessing of microelectronic workpieces, comprising: a bowl configuredto hold a plating solution; an anode assembly in the reactor at alocation to be in fluid communication with the plating solution in thebowl; a head assembly moveable relative to the bowl between a firstposition to load/unload a workpiece and a second position to place atleast a portion of the workpiece in the plating solution; and a contactassembly comprising a support member and a contact system, wherein thesupport member has a first section and a second section depending fromthe first section, the first section having an inner wall defining anopening configured to allow the workpiece to move through the supportmember along an access path, and the second section being defined by aplurality of posts depending from the first section, wherein the postsare separated from one another by gaps; and the contact system iscoupled to the posts of support member, wherein the contact systemcomprises a plurality of contact members projecting inwardly into theopening relative to the support member to contact a peripheral portionof the workpiece.